这样子写没有起作用:
int CALLBACK PropSheetCallback(HWND hDlg, UINT uMsg, LPARAM lParam)
{
   if(uMsg == PSCB_INITIALIZED)
   { 
      int   cx,cy;   
      RECT   rcFrame,rcPS;   
      GetClientRect(GetParent(hDlg),&rcFrame);   
      GetWindowRect(hDlg,&rcPS);   
      cx=((rcFrame.right-rcFrame.left)-(rcPS.right-rcPS.left))/2;   
      cy=((rcFrame.bottom-rcFrame.top)-(rcPS.bottom-rcPS.top))/2;   
      SetWindowPos(hDlg,HWND_TOP,cx,cy,-1,-1,SWP_NOSIZE );